Insulin
MedicationBasaglar, Lantus, Semglee, Toujeo, NovoLog, Fiasp, ReliOn
Antidiabetic hormone
Research strength: 4 / 5
ACOG recommends insulin during pregnancy to help control blood sugar, and the ADA says insulin should be used for type 1 diabetes and is preferred for gestational and type 2 diabetes. MotherToBaby says insulin aspart is not expected to increase miscarriage or birth-defect chances; the Lantus label says published glargine studies have not shown a clear association with miscarriage, birth defects, or other adverse outcomes. These sources describe pregnancy-wide evidence rather than a first-trimester-specific effect, and MotherToBaby and the Lantus label say poorly controlled diabetes can raise pregnancy risks. The FDA label for weekly efsitora says pregnancy use is not recommended because human data are insufficient; the EMA says people of childbearing potential should be advised to discontinue weekly icodec if pregnancy occurs or is desired because experience is lacking. Ask your provider about your situation.
Last reviewed: 2026-10-16
Sources
- American Diabetes Association, Standards of Care in Diabetes 2026, Section 15
- ACOG, Gestational Diabetes FAQProfessional society
- MotherToBaby, Insulin Aspart (NovoLog)Teratology service
- DailyMed, LANTUS insulin glargine injection labelDrug company label
- FDA-approved ONSWIK prescribing information, Section 8.1Drug company label
- EMA, Awiqli product information, Section 4.6EU agencyEuropean guidance
Research strength: 4 / 5
ACOG recommends insulin during pregnancy to help control blood sugar, and the ADA says it should be used for type 1 diabetes and is preferred for gestational and type 2 diabetes. The NovoLog label reports that five randomized trials involving 441 pregnant women found no association between aspart use in the second trimester and major birth defects or other adverse outcomes, while the Lantus label reports no clear association for glargine across published pregnancy studies. A 2011 multicenter study found similar maternal-fetal outcomes among women using glargine-based injections or an insulin pump, but it did not report a second-trimester-only effect. The FDA label for weekly efsitora says pregnancy use is not recommended because human data are insufficient; the EMA says people of childbearing potential should be advised to discontinue weekly icodec if pregnancy occurs or is desired because experience is lacking. Ask your provider about your situation.
Last reviewed: 2026-10-16
Sources
- American Diabetes Association, Standards of Care in Diabetes 2026, Section 15
- ACOG, Gestational Diabetes FAQProfessional society
- DailyMed, NovoLog insulin aspart injection labelDrug company label
- DailyMed, LANTUS insulin glargine injection labelDrug company label
- Bruttomesso et al., Type 1 diabetes control and pregnancy outcomes, 2011US government
- FDA-approved ONSWIK prescribing information, Section 8.1Drug company label
- EMA, Awiqli product information, Section 4.6EU agencyEuropean guidance
Research strength: 4 / 5
ACOG recommends insulin during pregnancy to help control blood sugar, and the ADA says it should be used for type 1 diabetes and is preferred for gestational and type 2 diabetes. MotherToBaby describes one study that reported more preterm births and babies smaller than expected with glargine; the study abstract gives no small-for-gestational-age estimate or clear comparison group, and it does not isolate third-trimester exposure. The Lantus label says published glargine studies have not shown a clear association with adverse pregnancy outcomes, while poorly controlled diabetes can raise pregnancy risks. The FDA label for weekly efsitora says pregnancy use is not recommended because human data are insufficient; the EMA says people of childbearing potential should be advised to discontinue weekly icodec if pregnancy occurs or is desired because experience is lacking. Ask your provider about your situation.
Last reviewed: 2026-10-16
Sources
- American Diabetes Association, Standards of Care in Diabetes 2026, Section 15
- ACOG, Gestational Diabetes FAQProfessional society
- MotherToBaby, Insulin GlargineTeratology service
- Chico et al., Glycemic control and maternal and fetal outcomes, 2016US government
- DailyMed, LANTUS insulin glargine injection labelDrug company label
- FDA-approved ONSWIK prescribing information, Section 8.1Drug company label
- EMA, Awiqli product information, Section 4.6EU agencyEuropean guidance
Insulin — Breastfeeding
Research strength: 4 / 5
LactMed says mothers using insulin may nurse, and a small milk study found exogenous insulin in milk from four mothers with type 1 diabetes. LactMed found no published information on infant drug levels or effects; the NHS Specialist Pharmacy Service says any insulin can be used while breastfeeding and recommends watching for signs of low blood sugar and monitoring infant weight gain. MotherToBaby says glargine and aspart are not expected to cause problems for breastfed infants, although it notes that these medicines have not been well studied in breastfeeding. FDA labeling says weekly efsitora use during breastfeeding is not recommended because human milk and infant-effect data are absent; EMA information says icodec's presence in human milk is unknown and infant risk cannot be excluded. Ask your provider about your situation.
Last reviewed: 2026-10-16
Sources
- LactMed, InsulinUS government
- Whitmore et al., Analysis of Insulin in Human Breast Milk, 2012
- NHS Specialist Pharmacy Service, Antidiabetic medicines during breastfeedingUK government
- MotherToBaby, Insulin GlargineTeratology service
- MotherToBaby, Insulin Aspart (NovoLog)Teratology service
- DailyMed, NovoLog insulin aspart injection label, Section 8.2Drug company label
- FDA-approved ONSWIK prescribing information, Section 8.2Drug company label
- EMA, Awiqli product information, Section 4.6EU agencyEuropean guidance
Pregnancy
The ADA states that insulin should be used for type 1 diabetes in pregnancy and is preferred for gestational and type 2 diabetes; ACOG also recommends insulin to help control blood sugar. Hod et al. (2008) randomized 322 women with type 1 diabetes to insulin aspart or regular human insulin and reported comparable fetal outcomes. Bruttomesso et al. (2011) studied 144 type 1 diabetes pregnancies and found maternal-fetal outcomes did not differ between glargine-based injections and pump treatment. Chico et al. (2016) analyzed 1,534 pregnancies and reported an association between glargine and preterm birth and small-for-gestational-age infants; its abstract gives no SGA estimate or clear comparison group and does not report a trimester-specific effect. The Lantus label says published studies have not shown a clear association between glargine and birth defects, miscarriage, or other adverse outcomes, but notes small samples and missing comparison groups. The NovoLog label summarizes five randomized trials involving 441 pregnant women and states that second-trimester aspart use was not associated with major birth defects or adverse maternal or fetal outcomes. FDA and EMA information contains product-specific pregnancy cautions for the weekly insulins efsitora and icodec; these statements address those products rather than the insulin class as a whole.
Breastfeeding
Whitmore et al. (2012) analyzed 24-hour milk samples from 14 mothers, including four with type 1 diabetes, and found exogenous insulin in milk from the type 1 group; the pilot study did not assess clinical infant outcomes. LactMed's August 2026 revision found no published information on infant drug levels or effects from maternal insulin use. NHS SPS says any insulin can be used during breastfeeding while recommending infant monitoring, and MotherToBaby says glargine and aspart are not expected to cause problems although these medicines have not been well studied during breastfeeding. The NovoLog label says a small study found insulin aspart in human milk but that information is insufficient to determine effects on a breastfed infant. FDA labeling does not recommend breastfeeding use of weekly efsitora, while EMA information says icodec may be present in milk and infant risk cannot be excluded.
Insulin is a hormone medicine used to control blood sugar. The live entry covers insulin as a class, including long-acting glargine and mealtime aspart, among other types.
What was tested
Pregnancy evidence includes randomized trials for insulin aspart and observational studies of glargine use; reported outcomes are not consistently separated by trimester. Breastfeeding evidence includes a small human milk study and clinical guidance, but LactMed found no published infant drug-level or outcome data as of its August 2026 revision. The weekly products efsitora and icodec have distinct product-label cautions because human pregnancy or milk data are limited or absent.
Class-wide insulin guidance and weekly insulin labels during pregnancy
- Source A says
- The FDA label says weekly efsitora use is not recommended during pregnancy because human data are insufficient. The EMA says people of childbearing potential should be advised to discontinue weekly icodec if they become pregnant or wish to become pregnant because clinical experience is lacking. (FDA-approved ONSWIK prescribing information, Section 8.1, EMA: Awiqli product information, Section 4.6)
- Source B says
- ADA says insulin should be used for type 1 diabetes and is preferred for gestational and type 2 diabetes in pregnancy. ACOG recommends insulin to help control blood sugar, and the EMA says Toujeo may be considered during pregnancy if clinically needed. (American Diabetes Association Professional Practice Committee: Standards of Care in Diabetes 2026, Section 15, ACOG: Gestational Diabetes FAQ, EMA: Toujeo product information)
- Why they differ
- The recommendations address different scopes. ADA and ACOG give class-level guidance for diabetes treatment, while the weekly-product labels address specific medicines with little or no human pregnancy experience. The FDA label cites insufficient human pregnancy data for efsitora, while the EMA icodec label cites lack of clinical experience.
- Other sources
- The Lantus label reports that published glargine studies have not shown a clear association with miscarriage, birth defects, or adverse maternal or fetal outcomes, while noting study limits. (DailyMed: LANTUS insulin glargine injection label)
- What the evidence shows overall
- Class-level guidance remains distinct from product-specific weekly-insulin cautions. The warnings for efsitora and icodec do not establish the same evidence profile for glargine, aspart, or every other insulin type.
Insulin use during breastfeeding and weekly insulin labels
- Source A says
- The FDA label says weekly efsitora use during breastfeeding is not recommended because human milk and infant-effect data are absent. The EMA says icodec milk excretion is unknown and a risk to infants cannot be excluded. (FDA-approved ONSWIK prescribing information, Section 8.2, EMA: Awiqli product information, Section 4.6)
- Source B says
- LactMed says mothers using insulin may nurse. NHS SPS says any insulin can be used during breastfeeding with monitoring, and MotherToBaby says glargine and aspart are not expected to cause problems for breastfed infants. (LactMed (NIH): Insulin, NHS Specialist Pharmacy Service: Using antidiabetic medicines during breastfeeding, MotherToBaby: Insulin Glargine fact sheet, MotherToBaby: Insulin Aspart (NovoLog) fact sheet)
- Why they differ
- The FDA and EMA statements concern distinct weekly medicines with limited human milk and infant information. LactMed, NHS SPS, and MotherToBaby summarize broader experience with insulin and common analogues, including small milk-level studies and monitoring guidance.
- Other sources
- A small human study found exogenous insulin in milk from mothers with type 1 diabetes, but it did not examine clinical infant outcomes; LactMed also found no published infant drug-level or outcome information. (Whitmore et al., Analysis of Insulin in Human Breast Milk, 2012, LactMed (NIH): Insulin)
- What the evidence shows overall
- The class-level breastfeeding guidance and the weekly-product label cautions can both be reported accurately. Evidence that insulin is present in milk does not by itself show clinical effects in an infant.
- ACOG says insulin is the recommended medication during pregnancy to help women control their blood sugar. (ACOG)
- NHS SPS says any insulin can be used during breastfeeding with monitoring; its recommendation applies to full-term, healthy infants. (NHS Specialist Pharmacy Service)
General research, not specific to pregnancy.
The FDA label for weekly ONSWIK identifies low blood sugar as the most common adverse reaction reported with that product.
- The ONSWIK label says hypoglycemia is the most common adverse reaction in patients using that product. (FDA-approved ONSWIK prescribing information, hypoglycemia section)
- MotherToBaby: Insulin Glargine fact sheetTeratology serviceSecondary
- MotherToBaby: Insulin Aspart (NovoLog) fact sheetTeratology serviceSecondary
- LactMed (NIH): InsulinUS governmentSecondaryPage dated 2026-08-15Independent check
- NHS Specialist Pharmacy Service: Using antidiabetic medicines during breastfeedingUK governmentSecondaryPage dated 2023-06-23Independent check
- ACOG: Gestational Diabetes FAQProfessional societySecondaryIndependent check
- American Diabetes Association Professional Practice Committee: Standards of Care in Diabetes 2026, Section 15Secondary
- DailyMed: LANTUS insulin glargine injection labelDrug company labelTertiaryIndependent check
- DailyMed: NovoLog insulin aspart injection label, pregnancy sectionDrug company labelTertiaryIndependent check
- EMA: Toujeo product informationEU agencySecondaryIndependent checkEuropean guidance
- FDA-approved ONSWIK prescribing information, Section 8.1Drug company labelSecondaryIndependent check
- EMA: Awiqli product information, Section 4.6EU agencySecondaryIndependent checkEuropean guidance
- Hod et al., Fetal and perinatal outcomes comparing aspart and human insulin, 2008US governmentPrimary
- Bruttomesso et al., Type 1 diabetes control and pregnancy outcomes, 2011US governmentPrimary
- Chico et al., Glycemic control and maternal and fetal outcomes, 2016US governmentPrimary
- Whitmore et al., Analysis of Insulin in Human Breast Milk, 2012PrimaryPage dated 2011-11-23
Last reviewed 2026-10-16
Independent check 2026-10-16
Not yet clinician-reviewed
Ask your provider about your situation.
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